Within the field of surgical repair of soft tissue defects such as hernias, use is often made of a mesh implant fabricated of a non-resorbable material that is inserted to cover the area of the tissue defect without sewing together the surrounding muscles. Such a mesh implant is most often made from various plastics, which are known to be biostable and safe for a number of years after implantation. However, it is known that such inert mesh materials can result in discomfort, inflammation, and recurrence of the hernia. Furthermore, permanently introducing a foreign material into the human (or animal) body could be accompanied with side effects such as migration, chronic inflammation, and chronic pain. The introduction of a relatively large inert implant is also likely to induce a long-term foreign-body-reaction caused by the body's immune defense system. As a result, the mesh implant may crumple up and lose its tissue supporting function.
An alternative approach is to make a mesh implant from a biodegradable polymer. Further, it is known to make a mesh implant from two different degradable polymers, either to improve the handling characteristics of such a mesh implant or to match the mechanical characteristics of such a mesh implant to the body's healing process of a hernia or other soft tissue defect.
For example, U.S. Pat. No. 6,162,962 to Hinsch et al. discloses an areal implant, which in one embodiment comprises a first resorbable polymer fiber arranged in a basic structure, into which a multifilament thread made from a second resorbable polymer has been woven for stiffening of the areal implant, to thereby facilitate handling during a medical implant procedure, e.g. when cutting to size and insertion. Here, the stiffening thread has a degradation time which is shorter than the degradation time of the polymer fibers of the basic structure.
Another example of degradable mesh implant is presented in U.S. Pat. No. 8,016,841, which is assigned to the present assignee and whose entire contents are incorporated herein by reference for the implant devices, techniques, materials, and methods disclosed therein. This patent describes a mesh implant made from at least two different polymeric fibers having different degradations times and also different moduli of elasticity, which are knitted together to form a mesh implant with time-dependent mechanical behavior. In this mesh implant, a first polymer fiber is arranged in a first knit pattern and a second polymer fiber is arranged in a second knit pattern, which is different from the first knit pattern and which locks movement of the first knit pattern. U.S. Published Applications 2006/0142786 and 2007/0299542 (now U.S. Pat. No. 8,083,755), which are assigned to the present assignee, also describe various implant devices, techniques, materials, and methods and their entire contents are incorporated herein by reference for the implant devices, techniques, materials, and methods disclosed therein.